Projection display systems have typically used ultra-high pressure (UHP) arc lamps to provide necessary light needed to project an image (or a sequence of images) on a display screen. The UHP arc lamps provide adequate brightness and have long life. Unfortunately, the UHP arc lamps consume a large amount of power and produce a lot of heat.
Recently, LEDs have come to market that have been able to produce light at intensity levels rivaling that of the UHP arc lamps, especially when multiple LEDs are used in conjunction. LEDs have an advantage in that it is possible to use narrow-spectrum LEDs that produce light with specific colors, whereas the UHP arc lamps produce broad-spectrum light. Additionally, LEDs consume less power and produce less heat when compared to the UHP arc lamps. Furthermore, LEDs tend to have longer life than UHP arc lamps.
One disadvantage of the prior art is that LEDs can be more expensive than UHP arc lamps. This can be further exacerbated by the fact that multiple LEDs may be required to replace a single UHP arc lamp due to the narrow-spectrum nature of LEDs as well as the LEDs' lower light output levels. This can lead to more expensive and complex display systems as well as potentially decrease reliability.
A second disadvantage of the prior art is that in order to optimize the power consumption of the LEDs, as well as increase useful life and light output, LEDs cannot simply be turned on. Drive currents for the LEDs may need monitoring as well as regulation and modulation. Therefore, driver circuitry may be needed to control the drive current of the LEDs. This can further result in a more expensive and complex display system.